Fork disassembly

Paul Musser · Post by **Paul Musser** » Thu Oct 15, 2009 3:10 pm

I'm attempting to replace the fork seals, and I'm having trouble getting the bolt out of the bottom of the fork. It turns, but the fork piston it's threaded into turns with it. On the GSs the top of the fork piston has internal hex sides (like a cap screw). The top of a spark plug socket fits it, so I can put a wrench with several extensions and an upside down spark plug socket down into the fork and hold that side, but the CBX doesn't seem to have that.

I've tried putting the spring back in, but it made no difference.

The bike has only 17,000 miles on it, so the forks have probably never been apart.

I'd appreciate any suggestions.

daves79x · Post by **daves79x** » Thu Oct 15, 2009 4:35 pm

Paul:
An air impact will break it loose, but if you put the spring back in and hit your Allen wrench with a hammer, it may break loose that way. I've had many apart, but have never had one turn.

Dave

Paul Musser · Post by **Paul Musser** » Thu Oct 15, 2009 6:35 pm

Thanks. I thought about an air impact wrench. I've been wanting to get one... maybe it's time.

It was odd because when I first put the wrench on the bolt (Allen socket in a 3/8 ratchet) it didn't want to turn at all. I had to put some major muscle in it before it finally, and suddenly, started to turn, but it wasn't just the bolt, it was the whole internal assembly. At that point, I tried hitting the wrench with a hammer, but it didn't help - the whole thing still turns.

Phil · Post by **Phil** » Thu Oct 15, 2009 6:43 pm

If all else fails, get a 3/8 dia. rod about 40 inches long. Bend 4 inches at a 90 degree for a handle. On the other end drill and press in a 1/8 inch dowel pin 1/2 inch from the end. Let it stick out about 3/16 inch. Insert the pin end of the rod down into the tube that spins and hook the dowel pin into a hole in the side of spinning tube. This will hold it in position while you unscrew the bolt.

Phil · Post by **Phil** » Thu Oct 15, 2009 6:46 pm

Really no big deal, takes a few minutes to make the rod and you will just have to play with it to find the hole in the side of the tube

Paul Musser · Post by **Paul Musser** » Thu Oct 15, 2009 6:52 pm

Phil wrote:If all else fails, get a 3/8 dia. rod about 40 inches long. Bend 4 inches at a 90 degree for a handle. On the other end drill and press in a 1/8 inch dowel pin 1/2 inch from the end. Let it stick out about 3/16 inch. Insert the pin end of the rod down into the tube that spins and hook the dowel pin into a hole in the side of spinning tube. This will hold it in position while you unscrew the bolt.

Thanks, I may end up having to do that. Since there's thread lock on that bolt, I can't see any way of getting it off without some way to hold the piston. I guess I could try drilling the head off, but I'm afraid I'll damage something else.

Paul Musser · Post by **Paul Musser** » Thu Oct 15, 2009 11:33 pm

Success! I took a tapered broom handle and wedged it into the top of the piston and it was enough to get the bolt out.

New challenge, though. I got the piston and rebound spring out, and removed the dust cover, circlip, and washer (and some odd thing under the dust seal that looked like a piece of rolled up paper towel). Then the manual says to 'remove the fork tube', but it won't come out. It comes most of the way, but then hits a hard stop. From the diagram it looks like it could be the bushing at the bottom of the tube. Should the tube just slide out? Do I have to slide it fast and bang it hard against whatever is hanging up? I don't want to damage anything, but it seems like it really doesn't want to get past that point.

Thanks again for the help.

daves79x · Post by **daves79x** » Fri Oct 16, 2009 4:31 am

Paul:
Yes, just use the tube as a slide hammer and the bushing and all will tap right out. If you are rebuilding both legs (you really should), make sure you install new seals and dust covers and make sure you didn't lose the copper sealing washer on the Allen bolt you had trouble getting out. When reinstalling, the seal has to go onto the tube before sliding the bushing into the leg. Get a piece of PVC pipe (11/2 or 2 inch - I can't remember), to use as a driver to install the bushing and seal. You can't obviously install the seal first like on the '79s. Then I'd go with 7wt fork oil, no heavier than 10wt, and fill each leg to 6 inches from the tube top with the fork collapsed and the spring out. This is more than the manual specifies, but works out very well.

The rolled up paper towel was probably just that - someone stuck it under the dust seal to absorb oil from the leaking seal.

Dave

Terry · Post by **Terry** » Fri Oct 16, 2009 6:06 am

Regarding this, "Then I'd go with 7wt fork oil, no heavier than 10wt'. I run 20w fork oil to go along with ProSus springs in my 79. Much less dive under braking and very little stiction. No wobbles on deceleration or at speed. Even with a fork brace, the forks are still kind of spindly so I use everything I can to make it handle as good as possible. BTW, a fork seal replacement by a qualified CBX mechanic with forks off doesn't cost that much...

:)

SteveG · Post by **SteveG** » Fri Oct 16, 2009 8:11 am

Terry wrote: BTW, a fork seal replacement by a qualified CBX mechanic with forks off doesn't cost that much... :)

Ah, but getting intimate with your significant other is half the fun

Steve

Paul Musser · Post by **Paul Musser** » Fri Oct 16, 2009 11:59 am

Thanks, I'll give it a try tonight. I am doing both legs. I expected it to go pretty smoothly - the ones I've done in the past have been pretty easy, but this is the first work I've done on the CBX and things are a little different. It's in really pristine, original condition, and I don't want to mess it up.

From all the posts I've read here and other sites, there does seem to be a wide range of recommendations for fork oil weight and volume. Once I get the seals replaced, I'll give one a try and see how it goes. It's easy to drain and fill with heavier or lighter oil.

Thanks, again.

Phil · Post by **Phil** » Fri Oct 16, 2009 5:01 pm

I`ve heard about the broomstick method others have used but never tried it, got to love improvising. I put in Prog. springs and I think 15 w oil in my 79, just didn`t seem to make much of a difference to me. Still nose dives badly.

Paul Musser · Post by **Paul Musser** » Mon Oct 19, 2009 12:22 pm

Well, the first fork is done. The second fork should be a breeze...

Thanks for all the help.

Terry · Post by **Terry** » Mon Oct 19, 2009 1:01 pm

..."From all the posts I've read here and other sites, there does seem to be a wide range of recommendations for fork oil weight and volume."

Keep in mind that the vast majority of these bikes you refer to are ridden very very infrequently. On the other hand mine is ridden quite frequently (thousands of miles annually) so my experience may be given more creedence than most others.